We propose to explore the components of the kinin-forming pathway in normal and malignant tissue. Specifically the presence of prekallikrein activators, kallikrein like enzymes and kininases in tissue will be investigated, utilizing synthetic substrates (esters of arginine or lysine) radioimmunoassay and bioassay techniques for the detection and quantitation of these activities. Once the components of the kinin generating system are isolated and purified their mode of action will be studied at the molecular level and their activities will be compared in normal and malignant tissues. BIBLIOGRAPHIC REFERENCES: Colman, RW, Bagdasarian, A. Talamo, RC, Scott, CF, Seavey M, Guinaraes, FA, Pierce, FV and Kaplan, AP. Human kininogen deficiency with diminished levels of plasminogen proactivator and prekallikrein associated with abnormalities of the Hageman factor dependent pathways. J. Clin. Invest. 56:1650, 1975. Colman, RW and Bagdasarian, A. Human kallikrein and prekallikrein. In: Methods in Enzymology, 1976, L. Lorand, ed., in press.